Clutch



June 20, 1939Q w. ls. WQLFRAM A CLUTCH 2 SheetsSheet 1 Filed March 11, 1958 June 20, i939. f w. s; woLFRAM 2,162,873

CLUTCH Filed MaICh 11:19:58 2 Sheets-Sheet 2 l [lli/[12H12 @Uffa/fz Gttornegs Summon:

Patented June 20, 1939 n as {r-'PATENT ori-ics utilizaral V- Wiliam s. wurm, mysan, om, amor to Icorporation of Delaware General Motors Corporation, Detroit,l Mich., a

Application March' 11,' iosaserni No. 195,291 n ls clams. (cum-163) i 'I'his invention relates to friction clutches for transmitting the drive from a driving shaft to a driven shaft, and particularly to .such clutches which are automatically engaged` by centrifugall force dependent on the speed of the driving shaft.

It relates particularly to such clutches in lthe masses which are subject to movement the inuence of centrifugal force yare operative in/conjunction with'dished sheet steel springs of the so-called'Belleville washer type to eieet'ensagement and disengagement of the clutch.

vBy suitable. dimensioning, and proportioning of the extent to which a Belleville washer is dished to the thickness of the material of it is made, a buckling spring or a spring may b e deflected from a condition in which itexerts a force in one direction to a condition in which it exerts a force in an opposite direction,

can be obtained.

One object of the invention is a clutch having a buckling spring which when buckled in one'direction is eiective to hold the relatively movable parts of the clutch in a disengaged position and when buckled inthe oppositedirection is ede'ctive -to hold the parts in an engaged position.v

Another object of the invention is a clutch in which bucklingy of the spring in a direction to eiect engagement of the clutch 1s resuiepuy reslated by a biasing spring yieldingly urging the buckling spring in a direction to effect disengage- :nent of the clutch.

clutch in which the buckling spring isc by speed responsive means from a cond parts in an engaged position. l

buckling spring to overcome the biasing:v and hold the parts in an engaged position The above and other objects of the invention will be apparent as the description proceeds.

The drawings show the application of the invention to a disc type centrifugal clutch.

lin the drawings' Fig. 1 is a Asectional view on line I- I .of Fig.' 4 of a clutch according to the invention, the parts being shown in the engaged position.

Fig. 2 is a view of a part of Fig. l showing the parts in the disengaged position.

Fig. 3 is a view on line 3--3 of Fig'. 1.

Fig. 4 is a front view of the clutch with parts broken away.

'Another object of the invention is anautomatic ,'eected i'tion in which it holds'the parts in a disengaged position to a condition in which it tends to hold the f The driving shaft l is provided with the driving disc member 2 which in the example illustrated, is an engine ilywheel. 3 is the driven disc'member having a'hub l' splinedfon the driven shaftl l. Rigidly bolted to the driving disc is the clutch 5 cover'i. y The pressure plate 6 is' driven from the clutch cover YI through suitable indentations I thereof, engaging grooves 8 in the periphery of the pressure plate, and is capable of axial sliding movel0 ment relative to the clutch cover 5. The pressure plate is provided with a plurality of guide posts 1 consisting of bolts such as IIVI, for Belleville washer vsprings II and I2, separated by a spacing ring I3. The Belleville washer spring Il is a l5 buckling Spring and the Belleville washer spring I2 is a biasing spring. y

The relative diameters and thicknesses of the springs II and I2 and the degree to which they are coned or dished is such that the spring I2 20 is somewhat stronger than spring I I. The spring H in its free condition is coned or dished in the direction shown in Fig. l, butconsiderably more so. 'I'he spring I2 in its free condition is coned or dished in the direction shown'in Fig. 2, but slightly more so. i Y

The biasing spring I2. has an abutment constituted by an annular bead I4 on the pressure plate 6,. and the buckling spring I I is clamped to an abutment or fulcrum ring l5 in an annular groove in the clutch coverv 5., by a pluralityof retaining springs such as I6. y

`Rigidly secured to the buckling spring II, as by rivets I9 at points close to its inner periphery.

-are a lplurality of yweights 28, suitablyspaced .and'disposed radially of the spring il, so thatwhen the driving shaft is running, the yweights have la centrifugal moment and there is a lresultant spring deecting, force-capable of deiiecting the inner periphery of the spring-relatively to its clamped outer periphery-stewards the pressure plate, against the pressure of theI biasing spring I2. l

A number` of Vleaf springs 24 have one end riveted to the clutch cover 5, with their Opposite ends bearing against a ring 25 which engages the heads 26 of the guide posts lo. The springs 24 tend to maintain the pressure plate in a position intermediate of' its fully engaged and fully disengaged positions, thereby cushioning engagement and disengagement of the clutch.

The spacing ring I3 serves to transmit the prefssure of the biasing spring l2 lto the buckling spring Il, and to transmit the pressure of the -spring Il plus the spring deiiecting force of the which under which which spring i nyweights 2o through the spring I: to the clutch:

pressure plate 8.

vAs shown most clearly in Fig. 3, the spacing 'ring I2 is cylindrical in shape, with roundededges,

and is notched as at 2B to clear the weights. It is provided also with a number of Ventilating holes such as 29.

As assembled, with the clutch disengaged and -inoperative as shown in Fig. 2, the spring II is coned in a direction opposite to its free condition.

.Acting on the buckling spring- II through the spacer ring I3, the biasing spring I2 is suiiiciently stronger than the buckling spring II to torce ity over center or past a ilatcondition. to a position 15 in which 1t is coned as' shown m Fig. 2.

In this condition the spring II is reacting against the retaining springs such as I6, and.

thrusting against the heads 2,6 of the posts I0l through the cushion springs 2l and the ring 25, holds the pressure plate 6 away from the driven disc 2', and the clutch disengaged. The spring I I and the spring I2 are both under a slight initial load with the former holding the clutch disengaged, while the latter is acting directly on the pressure plate 6 through the annular bead vI4 thereon, and reacting-indirectly on the pressure plate through the spacer ring I3, spring II,

springs 2l, ring 25 and the heads 26 of the posts Il, so that, of itself, it is without eiiect on the A position of thepressure plate 6.

When the driving shaft I is turned at a suillcient speed, the centrifugal moment of the flyweights 20 overcomes the force of spring I I tending to hold the clutch disengaged, moves the pressure plate 6 into contact with the driven disc I and the latter into contact with the driving disc 2 and then forces the spring II over center or past its flat condition after which the direction of force of this spring is reversed and added to that due to the centrifugal moment of the flyweights 2Il. The sum of these forces is transmitted through the spacer ring I2 to the spring I2, and thence to the pressure plate 6 through the annular bead Il thereon, to hold the clutch in engagement.

When the speed is reduced and the sum of the force of spring I I and that due to the centrifugal moment of the ilyweights 20 becomes less than 1 automatic engagement and disengagement of the clutch as thespeed of the driving member rises and falls. The clutch may for instance-be designed to be fully disengaged at speeds below 400 R. P. M. and fully engaged at speeds above 800` R. P. M.

I claim:

l. In a clutch mechanism, parts relatively mov able to engage and disengage the clutch, a buckling spring capable of being deflected from a condition in which it is eifective to hold the parts in a disengaged position to a condition in which it tends to hold the parts in an engaged posi' tion, and means for deflecting said buckling spring to the last named condition against the pressure of a biasing springv resiliently urging the buckling spring towards the ilrst named condition; said means'and sad buckling spring together exerting a force transmitted through the biasing spring, to hold the clutch engaged.

2. The combination according to claim l in which the buckling spring and the biasing spring are both Belleville washer springs. 3. The combination according to claim l in which the buckling spring is a Belleville washer and the means for deilecting said buckling spring to a condition in which it tends to hold the parts in an engaged position consists of a plurality of ilyweights rigidly secured to the buckling spring at points close to its inner-periphery and having a centrifugal moment such Athat there is a resultant force capable of deiiecting the spring in the required direction.

4. In a clutch mechanism, a driving member; a driven member; a buckling Belleville washer spring operative in one condition to yieldingly urge the driving member and the driven member into driving engagement, and in another condition to separate 'the driving member from the driven member and disengage the clutch; .and a biasing spring and speed responsive means diil'erentially controlling the said conditions of the buckling spring. I y

5. In a clutch mechanism, a driving member,

va driven member, a pressure plate mounted to rotate with the driving member but movable into and out of engagement with the driven member to engage and disengage the clutch. a buckling -spring capable of urging the pressure plate in opposite directions, towards and away from the driven member to engage and disengage the clutch, a biasing spring urging the buckling spring -in a direction to movel the pressure plate away from the driven member and means responsive to the speed of the driving member to urge the buckling spring in a direction to move the pressure plate into engagement with the .driven member.

WILLIAM S. WOLFltAM. 

